The invention involves a system for marking a material. In particular, the invention relates to an optical system for virtually marking features of a material along a processing dimension to facilitate automated processing of the material by a modifying device, such as a saw.
Automated saws are used extensively to cut materials for many different manufacturing applications. For example, saws may use a microprocessor to determine how to cut according to a user-supplied list of required dimensions i.e. a cut list. The microprocessor controls movement of a fence to locate for cutting in a manner that optimizes utilization of raw material. For some applications, the operator may need to mark defects, such as knots, cracks, or discolored portions of a material before cutting. The marked locations of defects allow the microprocessor to select cutting sites that exclude defects while making optimal use of the material according to the cut list requirements. Marking defects by measuring their location and inputting the locations along with the overall length of the material through the keyboard is time consuming and prone to operator error.
An improvement to this marking approach is described in U.S. Pat. No. 4,596,172 to Visser. In Visser, a user marks a wood product along its length with a marking instrument, such as a fluorescent crayon. The resulting mark is optically detected by a scanner unit mounted above the wood product. The scanner unit digitizes the position of each mark along the length of the wood product as it is conveyed past the scanner unit and sends this information to the microprocessor. This method of marking wood products is expensive to implement, and generally requires that the scanner unit be positioned far from the cutting site as the wood product is moved along a conveyer. The method may also result in unwanted marks on finished material.
Alternatively, a movable scanner unit may be used that tracks along the length of a stationary wood product. However, this movable scanner may require a movement mechanism that may be expensive and prone to mechanical difficulties. In addition, the period of time required for the scanner to move over the entire length of the wood product may be a rate-limiting step for inputting the defect locations of a wood product. Therefore, a simple and inexpensive assembly for use with an automated material processing system is still required to allow a user to quickly and accurately communicate the length and feature locations on a piece of material to an automated processing system.
The present invention provides an assembly for marking one or more feature locations along a processing dimension of a material. The assembly may use a light source that sends light along an optical path, and a light detector that receives light from the source. The device is configured to measure a feature location at a point along the optical path where light is reflected to the detector. A marking station orients the material so that the optical path is substantially parallel to the processing dimension of the material. Manual interruption of the optical path at a feature location communicates the feature location to a processor. The processor may be used to control a positioning assembly that moves the material relative to a modifying device such as a saw, based on the feature location and user-supplied processing requirements.